X-ray spectrochemical analysis, in conjunction with scanning or transmission electron microscopy, is often not used because conventional energy-dispersive crystal detectors are expensive and must be maintained at liquid nitrogen temperatures. These add considerably to the equipment purchase price and to a high and continuating operating cost. Cryo components are cumbersome and awkward to connect to some models of electron microscopes. R. J. Lee Group proposes to meet this need by developing a simple x-ray detector based on the principals of absorption x-ray spectroscopy and personal computer technology. The key to successful implementation of the technique will be verification that absorption filters for the lighter elements of importance in biological systems can be effectively calibrated by computer, eliminating many of the problems associated with the precise control of film thickness. The concept is based on coupling differential x-ray filters with a position sensitive detector an on-line computer processing of the count rates to provide a direct readout of elemental composition on anything from a personal computer to an array of digital panel meters. The Phase I project will demonstrate the feasibility of using differential filters to identify and quantify characteristic x-rays. Phase II of this project, these technologies will be brought together to develop a differential absorption x-ray spectroscopy system for identifying characteristic x-rays, and quantifying their intensities and will result in a simple and portable x-ray analysis system.